PCB association with model phospholipid bilayers.
We compare the association of an ortho-substituted and a planar PCB (polychlorinated biphenyls PCB-52 and PCB-77, respectively) with single-component phospholipid bilayers terminated with phosphocholine headgroups. First, fluorescence correlation spectroscopy (FCS) studies of diffusion on supported fluid-phase DLPC show that the ortho-substituted PCB diffuses more slowly, indicating either complex formation or obstructed diffusion. Differential scanning calorimetry (DSC) of vesicles formed from DMPC shows that the gel-to-fluid phase transition temperature is lower for vesicles containing this ortho-substituted PCB. Atomic force microscopy (AFM) shows that, whereas supported bilayers of DMPC containing this ortho-substituted PCB display two melting points, bilayers containing the coplanar PCB display just a single melting point. A model is proposed in which the ortho-substituted PCB resides within the lipid tails of these phospholipid bilayers but the coplanar PCB associates preferentially with the headgroups. This model is consistent with the known membrane disruptive ability of the ortho substituted isomer.
Campbell
Andrew S
AS
Department of Chemistry and Department of Materials Science and Engineering, University of Illinois, 600 S. Mathews Avenue, Urbana, Illinois 61801, USA.
Yu
Yan
Y
Granick
Steve
S
Gewirth
Andrew A
AA
D002152:Calorimetry, Differential Scanning; D004058:Diffusion; D008051:Lipid Bilayers / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D008956:Models, Chemical; D010743:Phospholipids / Q000737:chemistry*; D011078:Polychlorinated Biphenyls / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
D008051:Lipid Bilayers; D010743:Phospholipids; D011078:Polychlorinated Biphenyls